linux-kernel - Re: BUG: scheduling while atomic: ifup-bonding/3711/0x00000002 -- V3.6.7

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Message-ID: <50C24C44.8000809@tlinx.org>
Date:	Fri, 07 Dec 2012 12:06:28 -0800
From:	Linda Walsh <lkml@...nx.org>
To:	Jay Vosburgh <fubar@...ibm.com>
CC:	Cong Wang <xiyou.wangcong@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: BUG: scheduling while atomic: ifup-bonding/3711/0x00000002 -- V3.6.7

Sorry for the delay.... my distro (Suse) has made rebooting my system
a chore (have to often boot from rescue to get it to come up because
they put mount libs in /usr/lib expecting they will always boot
from their ram disk -- preventing those of use who boot directly
from disk from doing so easily...grrr.

Jay Vosburgh wrote:
> 	The miimon functionality is used to check link state and notice
> when slaves lose carrier.
---
    If I am running 'rr' on 2 channels -- specifically for the purpose
of link speed aggregation (getting 1 20Gb channel out of 2 10Gb channels)
I'm not sure I see how miimon would provide benefit.  -- if 1 link dies,
the other, being on the same card is likely to be dead too, so would
it really serve a purpose?


>   Running without it will not detect failure of
> the bonding slaves, which is likely not what you want.  The mode,
> balance-rr in your case, is what selects the load balance to use, and is
> separate from the miimon.
>   
----
    Wouldn't the entire link die if a slave dies -- like RAID0, 1 disk
dies, the entire link goes down? 

    The other end (windows) doesn't dynamically config for a static-link
aggregation, so I don't think it would provide benefit.

> 	That said, the problem you're seeing appears to be caused by two
> things: bonding holds a lock (in addition to RTNL) when calling
> __ethtool_get_settings, and an ixgbe function in the call path to
> retrieve the settings, ixgbe_acquire_swfw_sync_X540, can sleep.
>
> 	The test patch above handles one case in bond_enslave, but there
> is another case in bond_miimon_commit when a slave changes link state
> from down to up, which will occur shortly after the slave is added.
>   
----
    Added your 2nd patch -- no more error messages...

    however -- likely unrelated, the max speed read or write I am seeing
is about 500MB/s, and that is rare -- usually it's barely <3x a 1Gb 
network speed. (119/125 MB R/W).  I'm not at all sure it's really 
combining the links
properly.  Anyway to verify that?


    On the windows side it shows the bond-link as a 20Gb connection, but
I don't see anyplace for something similar on linux. 



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